Balloon dilation has been proposed as a procedure to repair stenoses, i.e., partial blockages of blood vessels. These blockages are generally caused by fatty deposits or calcified build-ups on the artery walls. Conventionally, arterial bypass surgery is performed when the blockages or partial blockages restrict arterial blood flow. A relatively recent alternative to bypass surgery is the use of balloon catheters in a procedure known as translumenal angioplasty.
Specifically, translumenal angioplasty is a method in which a balloon catheter is inserted into a partially blocked blood vessel. The catheter is threaded through the vessel to the location of the restriction and then briefly inflated to dilate the vessel permanently and thereby clear the restriction.
Each balloon catheter is designed to inflate to a known diameter, corresponding to the artery in which the procedure is to take place. The catheters are commonly inflated with fluids such as sterile saline solution, since gases should not be used intravascularly and do not give a known balloon displacement.
During angioplasty a catheter with a small balloon tip is passed through the blood vessel and the tip positioned at the restriction site. Correct positioning of the balloon tip at the stenosis site is accomplished through the use of fluoroscopy. The balloon is then inflated by forcing fluid through a connecting catheter tube to the tip. Since the inflated balloon effectively blocks the passage in which it is placed, rapid inflation and deflation are required to prevent the adverse effect of blood flow blockage. Any instrument used to control the balloon catheter should therefore be capable of rapidly inflating and deflating the catheter.
Several instruments relying on relatively complex mechanisms for catheter pressure control are in common use. Some have relatively complex ratchet or clutch arrangements that can be difficult to operate quickly enough under emergency conditions.
A need therefore exists for a simple, easy-to-use medical instrument instrument which allows quick control of balloon catheter inflation and deflation and which can be operated essentially instructively so that a doctor can react immediately to patient condition.